Jet Lag, Late Nights, And Naps Disrupt Gene Function, New Study Shows

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Business travelers, shift workers, college students, and overworked tech workers, beware. Unusual sleep patterns, particularly sleeping during the day and staying up late at night, wreak havoc with the activity of your genes, new research shows.

Researchers at the Sleep Research Centre at the University of Surrey in the UK interrupted study participants' sleep at regular intervals over three days, taking blood samples to monitor gene function. The findings: Daytime sleeping disrupted the rhythms of up to one third of the participants' genes.

Using a light-controlled sleep lab, Dijk and team manipulated the study participants' sleep patterns, postponing their bedtime by four hours a day until the subjects were 12 hours out of sync with their normal day/night biological clock. The purpose was to mimic the effects of jet lag or working the night shift, the researchers said.

Blood tests revealed decreased gene expression, which can affect the body's circadian rhythms, as well as bodily functions such as metabolism, inflammation, stress and immune response. Because genes carry the instructions for making proteins, which in turn make up the chemical signals and hormones that regulate the body, disrupted gene expression has profound implications for overall health.

Late nights are linked to gene disruption and serious health problems, new research shows. (Photo: wiki media)

The study, published online yesterday in the Proceedings of the National Academy of Sciences (PNAS), helps to shed light on the mechanism for previously established connections between interrupted sleep and serious health problems such as heart disease, obesity, diabetes, and cancer.

"This research may help us to understand the negative health outcomes associated with shift work, jet lag, and other conditions in which the rhythms of our genes are disrupted."said lead researcher Derk-Jan Dijk, professor of Sleep and Physiology and director of the Sleep Research Centre.

The research has worrisome implications not only for shift workers, but for business travelers, college students, and sleep-deprived workers of all stripes, who often nap or sleep during the day to make up for working late into the night. (As evidence, consider the fact that more and more companies are setting up nap rooms to offset employees' late work hours.)

And those long work days are taking their toll - according to the most recent poll by the National Sleep Foundation, 43 percent of Americans between the ages of 13 and 64 rarely or never get a full night's sleep during the work and school week.

In the past few years, scientists have been honing in on the connection between sleep patterns, light exposure at night, and serious health problems. Last year the American Medical Association (AMA) house of delegates went so far as to issue a policy statement warning that "nighttime electric light can disrupt circadian rhythms in humans" and that this disruption "affects aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism."

The AMA's concern was based, in part, on a growing body of new research linking working at night under bright lights with increased risk of breast cancer.

In a study published last year in Chronobiology International, researchers from Yale University and the Danish Cancer Society demonstrated that women who worked at night had the same epigenetic changes - biological changes that affect gene expression - previously observed in women with breast cancer. In 2007, the International Agency for Research on Cancer declared shift work a "probable human carcinogen."

While the current UK study was a small one, involving just 22 participants, previous research by Dijk and colleagues published last year also in PNAS documented similar findings.